The Section on Functional Neuroanatomy combines molecular and neuroanatomical methods to identify dynamic aspects of nervous system function that relate to issues of mental health, infectious disease, and drug abuse. Drug and neurotransmitter receptors are mapped using in vitro ligand binding and autoradiography. In situ hybridization histochemistry is used to localize and quantify mRNA expression of neuropeptides, monoamine transporters and synthesizing enzymes, receptors, cytokines, and immediate-early genes in studies of adaptive changes to behavioral, pharmacological, or surgical interventions. 1) The cannabinoid receptor has been localized and quantified in Huntington's and Alzheimer's brains. 2) Studies of animal models of chronic stress are designed to elucidate brain mechanisms involved in the therapeutic amelioration of stress disorders. Antidepressant drug administration and electroconvulsive shock are used in the animal models. Brain systems responsive to both stress and therapeutic treatment include the corticotropin-releasing hormone (CRH) component of the hypothalamic paraventricular nucleus (PVN), which controls the hypothalamic-pituitary- adrenal axis, and the noradrenergic locus coeruleus, which plays a role in arousal and vigilance. 3) Expression of the mRNA for the immediate- early gene c-fos was used to map brain sites responsive to injections of interleukin-1. Responsive cells in the brainstem suggest a pathway by which peripheral cytokines, as mediators of immune or inflammatory challenges, affect neuroendocrine responses. 4) Combinations of anatomical markers are used to reveal activity changes in hypothalamic arcuate nucleus neurons with known neuropeptide phenotype and identified projections to the PVN.